acquiescer
/əˌkwɪˈɛsər, əˌkwɪˈɛsɪsər/Definitions
1. verb
to consent or agree to something, especially unwillingly or in a submissive manner
“The government was forced to acquiesce to the demands of the protesters.”
2. noun
the act of consenting or agreeing to something
“Her acquiescence to the new policy was seen as a betrayal by her supporters.”